I'm going to use names from the story to explain this. Montresor makes certain to carry out his revenge on Fortunado himself. He wants Fortunado to know why he is being killed in such a slow and brutal way. If he hired other people to kill Fortunado, for example, then Fortunado will not understand that it is Montresor's revenge. So, based on this quote, we know that Montresor believes that revenge must be very clear, or it is not revenge.